Lyme disease due to the tick borne spirochete B. burgdorferi (bb) is a major emerging infection. It was originally recognized in children, and children continue to have a high rate of infection. Major issues concerning neurologic aspects of the disease in children and adolescents remain unresolved. Failure to understand the full spectrum of neurologic features has led to health care practices which may be both costly and ineffective. The objective of this proposal is to characterize the neurologic, cognitive and behavioral aspects of pediatric disseminated Lyme disease. Case group two will meet the CDC surveillance criteria for extrameural Lyme disease (Lyme arthritis, carditis or multifocal erythema migrans). Control group three will be composed of an age-sex and IQ-matched of healthy Bb seronegative controls. All three groups will have neurologic , neuropsychologic, behavioral and psychosocial evaluations at entry. Subjects with neurologic involvement will have cerebrspinal fluid (CSF) studies. Disseminated Lyme disease subjects will receive recommended antibiotic treatment. All three groups will be followed prospectively with full re-evaluation at 18 months. This project will establish the relative frequency, severity and progression of neurologic and neurobehavioral disturbances associated with pediatric Lyme disease, thereby helping to standardize care and reduce medical costs, as well as increase our understanding of underlying pathophysiologic mechanisms of this disorder.